#define _CRT_SECURE_NO_WARNINGS 1
#include <cmath>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include<math.h>
#include<stdlib.h>
#include<stdio.h>
#include<unordered_map>
using namespace std;

class Solution {
public:
    bool isUnique(string astr) {
        if (astr.size() > 26) return false;
        int bitmap = 0;
        for (auto& ch : astr)
        {
            int tmp = ch - 'a';
            if (((bitmap >> tmp) & 1) == 1) return false;

            bitmap |= (1 << tmp);
        }
        return true;
    }
};

int main() {
    return 0;
}